1. Field of the Invention
The present invention generally relates to a stage device, an exposure apparatus using the same and a device manufacturing method, wherein the exposure apparatus is preferably used in a lithography process for manufacturing micro-devices.
2. Description of the Related Art
In a lithography process for manufacturing micro-devices (e.g., semiconductors), two types of exposure apparatuses are known. One is a step-and-repeat type (so-called a stepper) and the other is a step-and-scan type (so-called a scanner or a scanning type exposure apparatus).
The former type uses a step-and-repeat sequence for transferring stepwise a pattern of an original (e.g., a reticle or a mask) onto a substrate (e.g., a semiconductor wafer or a glass or silicon substrate). In that sequence, the whole pattern of the original is illuminated and is projected onto one of a plurality of exposure regions on the substrate through a projection optical system, while the original and the substrate are maintained stationary. Next, the substrate is moved stepwise to change the exposure region, and then exposure is repeated in the same manner.
On the other hand, the latter type uses a step-and-scan sequence. In that sequence, an original pattern is illuminated with a slit-like beam and a portion of the pattern is projected onto one of a plurality of exposure regions on a substrate, while both the original and the substrate are scanningly moved. Next, the substrate is moved stepwise to change the exposure region, and then exposure is repeated in the same manner.
The step-and-scan type exposure apparatus seems to have become the mainstream, at least for the near future, for the reason that it has a potential for high exposure performance in terms of an increase in transferring precision and field size.
These types of exposure apparatuses include stage devices (e.g., a wafer stage or a reticle stage) for moving and positioning the wafer or the reticle rapidly. However, when the stage moves with a high rate of acceleration (positive or negative), a reaction of an inertial force occurs and this can cause vibration of not only a base which supports the stage, but also a floor which supports the whole exposure apparatus. This vibration might cause a natural oscillation of the mechanical system of the exposure apparatus and that disturbs the positioning of the stage.
The acceleration of the stage movement has recently been increasing more and more as a result of progress in the throughput (processing speed) in an exposure operation. In the step-and-scan type exposure apparatus, the maximum acceleration has reached as much as 4 G (for the reticle stage) and 1 G (for the wafer stage), for example. Furthermore, due to an increase in the original size and the substrate size, the stage mass has been increasing. For these reasons, a driving force, as defined by the stage mass multiplied by the acceleration, has become enormous, and that means the reaction of the driving force has also become enormous. Consequently, the vibration of the floor as described above has become an actual challenge to be solved.
In view of above-described recognition about the prior art, a primary object of the present invention is to provide a stage device that is superior to the conventional apparatus.
To improve the conventional apparatus, the inventors propose to apply a hollow structure to a movable portion of the stage device, in order to reduce its mass. Such a hollow structure, however, is apt to produce a resonance itself and is apt to transmit vibrations through itself, for the reason of a lack of rigidity as compared with a structure without a hollow structure. Therefore, we prefer to apply the hollow structure to the stage device with some improvements. Accordingly, another object of the present invention is to provide a stage device having a hollow structure that is consistent with maintaining the stage performance and structural integrity of the stage device.
Yet other objects of the present invention are to provide an improved exposure apparatus using such a stage device, and a method for manufacturing semiconductor devices.
In order to achieve the above objects, the present invention, in a first aspect, provides a stage device including a movable body, movable along a guide surface, for moving an element mounted on the movable body, a static pressure bearing, having at least one pad, for guiding the movable body along the guide surface, the at least one pad being attached to the movable body at a first position, and a linear motor, having a movable part and a relatively stationary part, for moving the movable body, the movable part of the linear motor being attached to the movable body at a second position, wherein the movable body has a hollow structure at at least one of the first position and the second position.
The present invention, in another aspect, provides an exposure apparatus comprising an illumination system for illuminating a substrate with radiation, and a stage device including a chuck for holding the substrate to be exposed, the stage device including a movable body, movable along a guide surface, for moving an element mounted on the movable body, a static pressure bearing, having at least one pad, for guiding the movable body along the guide surface, the at least one pad being attached to the movable body at a first position, and a linear motor, having a movable part and a relatively stationary part, for moving the movable body, the movable part of the linear motor being attached to the movable body at a second position, wherein the movable body has a hollow structure at at least one of the first position and the second position.
The present invention, in still another aspect, provides a device manufacturing method for manufacturing micro-devices, the method comprising illuminating a substrate with radiation, using an illumination system, moving an element mounted on a movable body of a stage device of an exposure apparatus, the movable body being movable along a guide surface, guiding the movable body along the guide surface using a static pressure bearing, having at least one pad, the at least one pad being attached to the movable body at a first position, moving the movable body with a linear motor, having a movable part and a relatively stationary part, the movable part of the linear motor being attached to the movable body at a second position, wherein the movable body has a hollow structure at at least one of the first position and the second position, and exposing the substrate with radiation to manufacture micro-devices.
According to the present invention, since at least a portion of the movable body, where at least one of the pad and the movable part of the linear motor is attached, has a hollow structure, it is possible to improve the performance of the stage device, such as high controllability, reduction of settling time and high positioning accuracy. Hence, the present invention improves performance (e.g., total throughput and exposure accuracy) of the exposure apparatus and increases productivity of the micro-device manufacturing.